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1. Technical Field
The present invention relates generally to a system and method for securing tumbler locks. More particularly, the invention relates to a keyhole barrier system and method which prevents the operation of a tumbler lock.
2. Description of the Related Art
A conventional tumbler lock system allows any user with a matching key to operate the lock. Under normal conditions, operation of the lock by authorized individuals is completely appropriate. There are circumstances, however, in which it is necessary to prevent a normally authorized individual from accessing an area which may be entered through a door having a tumbler lock. For example, when a house is being fumigated, the owners of the home are not permitted to enter the premises for a period of time. Exclusion from the house is required to prevent exposure to harmful residual chemicals resulting from the fumigation procedure. Once the chemicals have dissipated, it is safe for the owners to return. A keyhole barrier system plays an important role in preventing the owners from entering during the harmful period.
It is known to insert a keyhole block into a door to prevent individuals from entering an area, including those individuals who possess the proper key. For example, U.S. Pat. Nos. 1,573,791 and 1,696,326 to Roethlisberger, U.S. Pat. No. 1,728,310 to Sundel, U.S. Pat. No. 3,276,233 to Russell et al., and U.S. Pat. No. 3,408,842 to Barnes et al. all disclose keyhole blocking devices for tumbler locks. Notably, the Roethlisberger, Russell and Barnes devices contain a keyhole block portion which is completely inserted into the keyhole and is invisible from the outside of the lock when installed. Thus, no portion of these keyhole blocks can serve as a visible warning device to an individual attempting to open the lock. Therefore, what is needed is a keyhole barrier system which integrates a warning device into the keyhole block portion of the system.
It is an object of the present invention to provide a keyhole barrier system which prevents individuals from entering an area which is unauthorized.
It is another object of the present invention to integrate a warning device into the keyhole barrier system to prevent individuals from entering a hazardous area, such as a room that has recently been fumigated, thereby preventing exposure to a harmful environment.
It is a still further object of the present invention to integrate the warning device into a portion of the system which blocks a tumbler lock, thereby preventing removal of the warning device from the lock.
Other objectives and applications of the present invention will become apparent from the following description contained in the accompanying specification. The preferred embodiments are not intended to be limiting, but are solely for illustrative purposes.
In accordance with the invention, a keyhole barrier system for use with tumbler locks is provided. The system can be used on tumbler locks having a keyway, a plurality of tumblers in the keyway and a lock surface outside of and surrounding an opening of the keyway. The system includes a keyhole block having a retention portion and an external signaling portion. The retention portion can contain an angled tip and also a longitudinal axis and can be designed to prevent the removal of the keyhole block from the tumbler lock once the retention portion is installed in the keyway. The retention portion can be inserted into a tumbler lock along a longitudinal axis of the keyway. The signaling portion can extend from the retention portion of the keyhole block in a non-perpendicular manner. Further, when the keyhole block is installed into a keyway, the signaling portion can extend outwardly from the keyway and provide a readily observable warning to approaching observers that the keyhole is blocked.
The signaling portion of the present invention can provide a warning for individuals approaching the lock. The signaling portion preferably has a height greater than either the axial height of the retention portion or the elongated height of the retention portion. When the keyhole block is inserted into the lock, the signaling portion can extend substantially parallel to the longitudinal axis of the retention portion. Also, the signaling portion can be visible laterally relative to a longitudinal axis of the retention portion. Further, the signaling portion can extend substantially perpendicular to the lock surface. Such a signaling portion can be of unitary construction with the keyhole block, such as an extension of the retention portion projecting outward from the lock when the keyhole block is installed.
The signaling portion can comprise attachment structure containing, for example, an aperture or a label mount. A warning label can be affixed directly to the signaling portion of the present invention. In one embodiment, a warning label, such as a sticker, can be affixed to the signaling portion extension. The signaling portion may also contain a label mount. The label mount can take the form of an aperture through which a label is attached. The label mount may be used to attach warning labels of different sizes and shapes to the signaling portion. This label mount may be used, for example, to attach warning labels informing unauthorized individuals not to enter an area recently fumigated.
The present invention can also contain an extractor to facilitate removal of the keyhole block. The extractor can be used to displace the tumblers of the lock in order to facilitate removal of the keyhole block from the tumbler lock. The extractor can have a handle portion and a center edge. The extractor can matingly interfit with the keyhole block during retraction of the keyhole block from the keyway. The handle portion and the signaling portion can, in combination, form a retraction aid, thereby facilitating removal of the keyhole block from the keyway. Additionally, the system can include fastening structure for keeping the system components in close proximity to each other when not installed.
A method for forming a barrier in a tumbler lock keyhole is also provided. The method includes a keyhole block having a retention portion and a signaling portion. The retention portion can be comprised of an elongated portion, a locking surface and a tip. The retention portion can be inserted along a longitudinal axis of the keyway. The signaling portion can extend outward from the tumbler lock substantially parallel to the retention portion once the keyhole block is installed. The method further comprises inserting the keyhole block into the tumbler lock and allowing at least one pin from the tumbler lock to drop behind the tip of the retention portion and lock in place. Thus, the tumbler lock cannot be operated using a conventional key once the keyhole block is in place. Additionally, the method comprises a signaling portion which serves as a visible warning to individuals approaching the lock. A label mount can be provided with the signaling portion for attaching warnings regarding the installation of the keyhole block.
An extractor having a handle portion can also be provided. The extractor can matingly interfit with the retention portion and displace the pins which have locked against the locking surface of the keyhole block. Further, the handle portion and the signaling portion can engage to form a retraction aid. A user can grip the retraction aid to remove the system from a keyway. Fastener means can also be provided to keep the signaling portion and the handle portion in close proximity to each other when the system is not installed.